Add a new ThreatSource type to indicate SBHit is from client side detection.

chrome/browser/safe_browsing/ping_manager.cc

Index: chrome/browser/safe_browsing/ping_manager.cc
diff --git a/chrome/browser/safe_browsing/ping_manager.cc b/chrome/browser/safe_browsing/ping_manager.cc
index 4caf329cb15dbcc2b9463d62468eacc969e7351f..001d08f6ca994cdfe6d2bcb94c1baa74e375bd7b 100644
--- a/chrome/browser/safe_browsing/ping_manager.cc
+++ b/chrome/browser/safe_browsing/ping_manager.cc
@@ -191,6 +191,9 @@ GURL SafeBrowsingPingManager::SafeBrowsingHitUrl(
     case safe_browsing::ThreatSource::LOCAL_PVER4:
       threat_source = "l4";
       break;
+    case safe_browsing::ThreatSource::CLIENT_SIDE_DETECTION:
+      threat_source = "csd";
+      break;
     case safe_browsing::ThreatSource::UNKNOWN:
       NOTREACHED();
   }